The invention relates to a steering column arrangement for a motor vehicle and, in particular, to a steering column arrangement having a steering spindle and a blocking device against which a blocking element is mounted in a relatively moveable manner.
It is known from the mass production of motor vehicles that during a front end collision the forces act on the front wheels, a state that under some circumstances causes the introduction of an undesired rotational motion in the steering wheel by way of the tie rod and the steering linkage.
The German published patent application DT 2359943 A1 describes a measure in order to eliminate the so-called “wobble” movement of the steering wheel. To this end, the parts of the front section of the vehicle are constructed in such a manner that if, owing to a front end collision, the front section of the motor vehicle is displaced in the direction of the passenger compartment, the parts of the front end section act on the parts of the steering linkage in the sense of blocking the steering. Therefore, the front cross support has blocking elements in the form of guide elements, which slide over the steering pitman arm in the event of a collision. Thus, the steering is blocked, and the rotational motion, acting on the steering wheel, is eliminated.
A prerequisite for this type of blocking is that the front section of the vehicle shifts uniformly in the direction of the passenger compartment. Thus, for example, in the event of a front end collision, blocking may be guaranteed under some circumstances only with additional measures.
The object of the invention is to provide a steering column arrangement, which functions reliably with minimum complexity even in the event of a front end collision.
According to the invention, a steering column arrangement for a motor vehicle is provided with a steering spindle, which rotates about its longitudinal axis and serves to transfer a torque, generated by the steering wheel, to a steering gear. Furthermore, the invention provides a blocking device, which prevents the rotational motion of the steering spindle, especially in the event of a collision. To this end, the blocking device includes a stator, which is stationary in relation to the rotational motion of the steering spindle. A blocking element is moveable against the stator into a locked position in a radial direction directly to the steering spindle. Advantageous embodiments are described and claimed herein.
Owing to the inventive arrangement of the blocking device, there is no need for a coupling to the steering gear in order to block the rotational movement of the steering wheel. There is no need to deform the front section in order to prevent an undesired rotational motion of the steering wheel. It suffices if, in the event of a detected impact, the blocking element is activated by way of a control unit, which is well-known. A stator is required—that is, a component, which is stationary in relation to the rotational movement to the steering spindle, such as a steering spindle housing or a bracket for coupling the steering column to the cockpit cross support. The blocking element is mounted in such a manner that it moves relative to the stator and can assume two positions: a locking position, in which the rotational movement of the steering spindle is eliminated, and an unlocked position—thus, a normal position—in which the steering spindle transfers the rotational movement, applied by the driver on the steering wheel, to the steering gear.
In order to achieve a blocking of the steering spindle and, thus, the steering wheel, the blocking element may interact in a shape-locked manner with the steering spindle in the locked position.
As an alternative, a friction-locked interaction is also contemplated.
The blocking device may also advantageously include a housing, which is also attached in a relatively moveable manner to the stator. Thus, the steering spindle may be attached to both the blocking element and the housing itself.
In a preferred embodiment, the blocking element is mounted in a displaceable manner in the housing. As an alternative, the blocking element may be hinged. The blocking element is then pivoted about this coupling point in the direction of the steering column, in order to bring the blocking element into the locked position.
If an overpressure is generated, for example, by use of a pyrotechnical device or by use of a compressed air source in an interior, adjacent on the back to the blocking element, the blocking element may be moved in the housing in the direction of the steering spindle. If the blocking element is activated early, the drive for the blocking element may also be replaced by other alternatives, such as a mechanical drive.
For the shape-locked engagement, the blocking element may exhibit on its face side, facing the steering spindle, an internal toothing, which engages with a toothed ring of the steering spindle in the locked position.
Another preferred embodiment consists of the fact that the housing is held under prestress in such a manner that it moves relative to the stator. Thus, in the event of a misfiring, the housing can move back again by itself into its normal position.
A higher blocking force may be achieved if an inner wall region of the housing that faces the steering spindle also exhibits an internal toothing, which in the locked position of the blocking element engages with the toothed ring of the steering spindle. In the locked position, the internal toothing of the housing and of the blocking element may enclose almost completely the toothed ring of the steering spindle.
The activation of the blocking element may ensue by means of a signal, which is generated by a signal generator in the event of an impending collision or following a collision. This signal generator may be, for example, a control unit of an airbag unit.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description when considered in conjunction with the accompanying drawings.